Platen for typewriters, adding machines, and the like



Dec. 16, 1941. H. SCHULER PLATEN FOR TYPEWRI'I'ERS, ADDING MACHINES, AND THE LIKE Flled Jan 21 1959 Patented Dec. 16, 1941 PLATEN FOR TYPEWRITERS, ADDING MACHINES, AND THE LIKE Hugo Schiller,

Schonau, near Chemnitz, Germany, assignor to Wanderer-Werke Aktiengesellschaft, Siegmar-Schonau, Germany Application January 21, 1939, Serial No. 252,184 In Germany January 31,.1938

a 2 Claims.

The present invention relates to a platen for a typewriter, calculating and other oflice machines. An object of the invention is to provide a platen-structure which will lighten the platen and make easier the manufacturing thereof as well as reduce the noise as much as possible. This is accomplished by providing ribs on the core of the platen, which ribs are preferably integral with the material of the core. It is another object of the invention to provide a better construction of the platen. For accomplishing this and for further damping the noise the hollow core cylinder is composed of a plurality of longitudinal parts.

Other objects will be apparent from the following description taken in connection with the accompanying drawings in which:

Figure 1 is a longitudinal sectional view of one form of the platen according to the invention,

Fig. 2 is a cross sectional view of the platen taken on line 2-2 of Fig. 1,

Fig. 3 is a perspective view of a half part of a modified construction,

Fig. 4 is a cross sectional view of the complete platen taken on line 4-4 of Fig. 3, and

Fig. 5 is a cross-sectional view similar to Fig. 4 showing a modified detail.

The platen, which in particular is a printing base for the types of typewriters, calculating and other business machines consists essentially of a core 1, Figs. 1 and 2, on which a rubber layer 2 is provided. Usually a flange-like holder 3 is provided on each end which holders are secured to the core l by means of screws 4 or other suitable means. It is the usual practice to have the bearing pins (not shown) or a shaft (not shown) provided in these holders or bearings 3 in order to rotatably mount the platen in themachine in any well known manner.

In the form of construction according to Figs.

1 and 2 the core I consists of a hollow cylinder.

which has internal ribs 5 preferably integral with the core. These ribs 5 increase the strength and rigidity of the core and thus decrease its tendency to vibrate. Also the ribs tend todecrease and damp the sound vibrations. in the internal v It is therefore suitable that space of the core. the ribs 5 shall be provided obliquely to the longitudinal direction of the core I. These ribs produce the best results when they are in such form that a plurality of helically directed ribs cross each other. Thereby the result is produced that individual sections are formed internally of the hollow cylinder which prevent the travel or expansion of the sound waves particularly along casting a synthetic or artificial material or other non-metallic materials and can also be produced by methods other than casting, e. g. die casting or pressing.

An important improvement in the production of the platen as well as a very good damping of the noise produced during use can be attained by dividing the core in a number of parts in the longitudinal direction. The parts can be individu ally manufactured and when so produced there will be formed slight irregularities in the meetin or contacting surfaces of the parts forming small hollow spaces. Thus the-individual parts of the core contact only at a plurality of points and thus a platen is produced which in use will at most give out a particularly muffled noise which is not in the least objectionable.

For this purpose the platen core is suitably made of two parts la and lb, Fig. 4, and these two halves, of which one is shown in Fig. 3, can have the same form. This has the advantage that in manufacturing the platen it is only necessary to have but one-half of a mold or form in which the two parts are individually cast or drop forged.

Naturally it is possible to divide the core into more than two parts, whereby the advantages of a small-mold or form in the manufacture and the greater noise damping attained are increasingly evident.

The ribs 5a and 5b, Figs. 3 and 4, are made in criss-cross form for each core half in such a manner that upon placing the two halves together the ribs 5a and 51) will meet suitably end to end and cross at the meeting surfaces of the halves.

The individual parts or halves of the core are provided with suitable raised or depressed portions, aligning parts or members, which lntergrlp or connect each other to securely maintain the halves in positive alignment. These interconnections of the individual parts or halves can also be attained by screws, bolts or other suitable means.

A better damping of.

It is of course advisable to cast or soft rubber.

provide the interconnecting means at the time of making or forming the parts or halves so that no essential manufacturing step is necessary after casting or forming the halves.

This key or interconnecting means can for example consist of small pins i, Figs. 3 and 4, which may be secured in the core halt in or may be cast therewith. The pins can also be inserted after the halves are made and these pins project in suitable perforations or holes I drilled into the half lb or otherwise formed in the same. The projections or pins 8 and the depressions or drilled holes I. can be so formed that upon assembling the two parts in and lb a clamping action takes place due to a tight fit oi. the pins I so that no other securing or holding means for the halves is necessary.

By fine die or pressure casting, or other step such a precision can be attained that no final finishing step is necessary. The finished cast, die cast or pressed core parts in and lb are simply assembled together and over the thus produced core a cover or layer 2 of rubber or any "other suitable resilient material is provided which can be merely pulled over or wound around the two halves and it can be vulcanized thereon if desired.

The cover 2 is then treated and prepared on the surface thereof so that the platen will accurately rotate on a true circumferential plane. Naturally many rubber layers can be provided and likewise other intermediate layers can be applied such as Thereby it is of course suitable to make the outer layer the most resistive to wear. It is also possible to provide thin intermediate layers of rubber, felt, paper, and other noise damping materials between the individual parts or halves of the core.

The pins 8 and the perforations 1 can be provided at such parts of the halves or parts In and lb that upon assembling two halves the pins and perforations will match, that is the pins of one part will enter the perforations-oi the other part so that it will not be necessary to provide special pins and both halves la and lb can be made alike, e. g. by means of the same mold. Fig. 5 shows those platen core halves la, lb of the same configuration the upper edges oi. which are provided with holes 1' whereas their lower edges show pins C.

. To assemble these equal parts la, lb or the core, they must be turned round an axis-vertical to their meeting surfaces 180 against each other, to make the corresponding pins i fit into the corresponding holes 1'.

I claim as my invention:

1. A platen for typewriters and the like comprising in combination a one part cylindrical resilient cover, two semi-cylindrical parts forming a hollow cylinder carrying said cover, a disc member secured at each end of the cylinder, each disc member having means for supporting the platen, and a plurality oi noise damping ribs on the internal surfaces or and integral with the semi-cylindrical parts, said ribs projecting into and ending in the cavity of the cylinder without contacting any other parts.

2. Platen according to claim 1, in which the ribs are arranged in zigzag fashion on the internal surface of each semi-cylindrical part.

HUGO SCHULER. 

